On Site Guide intelligence
Pirform's intelligence incorporates the following guidance from the IET's On-Site Guide, specifically Table 7.1(ii). Read more here.
Ring Final Circuits
The following ring final circuits configurations are recognised by cable-sizing rules.
Rating | Standard | Live | CPC | Reference Method | TN-S 30 mA RCD | TN-S No RCD | TN-C-S 30 mA RCD | TN-C-S No RCD |
---|---|---|---|---|---|---|---|---|
30 | 3036 | 2.5 | 1.5 | 100, 102, A, C | 106 | 41zs | 106 | 106 |
30 | 3036 | 4 | 1.5 | 100, 102, A, 101, 103, C | 171 | 48 | 171 | 138zs |
32 | CB (60898 B, C, & D) | 2.5 | 1.5 | 100, 102, A, C | 106 | 96zs | 106 | 106 |
32 | RCBO (61009 B, C, & D) | 2.5 | 1.5 | 100, 102, A, C | 106 | NPzs | 106 | 56zs |
32 | 88-2 | 2.5 | 1.5 | 100, 102, A, C | 106 | NPzs | 106 | NPzs |
32 | 60269-2 | 2.5 | 1.5 | 100, 102, A, C | 106vd | 32zs | 106vd | 106vd |
32 | 88-2 | 4 | 1.5 | 100, 101, 102, 103, A, C | 171 | 38zs | 106vd | 127zs |
32 | 60269-2 | 4 | 1.5 | 100, 101, 102, 103, A, C | 106vd | 19ad | 106 | 95zs |
32 | 88-3 | 2.5 | 1.5 | 100, 102, A, C | 171 | 22zs | 171 | 112zs |
32 | 88-3 | 4 | 1.5 | 100, 101, 102, 103, A, C | 171vd | 114ZS | 171vd | 171vd |
32 | CB (60898 B, C, & D) | 4 | 1.5 | 100, 101, 102, 103, A, C | 171vd | NPzs | 171vd | 66zs |
32 | RCBO (61009 B, C, & D) | 4 | 1.5 | 100, 101, 102, 103, A, C | 171vd | NPzs | 171vd | NPzs |
The following abbreviations are used in the table above:
- CB: Circuit breaker
- RCBO: Residual current circuit breaker with overcurrent protection
- TN-S: Terra neutral - separate
- TN-C-S: Terra neutral - combined and separate
- RCD: Residual current device
- vd: Voltage drop
- ad: Adiabatic limit
- zs: Earth fault loop impedance
- sc: Line to neutral
- NP: Not permitted
- NPvd: Not permitted (prohibiting factor: voltage drop)
- NPad: Not permitted (prohibiting factor: adiabatic limit)
- NPzs: Not permitted (prohibiting factor: earth fault loop impedance)
- NPsc: Not permitted (prohibiting factor: line to neutral)